Device for overcoming dead-centers.



PATENTBD MAY '7, 1907.

F. W; DILL' & J. R. HILL.

DEVICE FOR OVERCOMINC DEAD CENTERS.

APPLICATION FILED FEB.23,1906.

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5 vweulorks UNITED STATES PATENT OFFICE.

FREDRIOK W. DILL AND JOHN R. HILL, OF LINCOLN, KANSAS.

DEVICE FOR OVERCOIVIING DEAD-CENTERSu Specification of Letters Patent.

Patented May 7, 1907.

Application filed February 28,1906. Serial No. 303,533.

To all whom it may concern:

Be it known that we, Fnnnnrcx W. DILL and JOHN R. HILL, citizens of the United States, residing at Lincoln, in the county of Lincoln and State of Kansas, have invented certain new and useful Improvements in Devices for Overcoming Dead-Centers, of which the following is a specification.

In the operation of sewing machines, lathes and similar devices where power is transmitted from a reciprocating member to the rotary member by means of a pitman, much difficulty is commonly experienced owing to the fact that when the wrist pin is in alinement with the pitman, a dead center is produced.

Our invention has for its object to overcome this difficulty by means of a simple device which can be readily applied to any pitman and which can be manufactured at a very small cost.

Broadly speaking, the invention comprises a spring member which extends along the pitman and has one end loosely connected thereto while the opposite end is rigidly secured to the reciprocating part.

For a full description of the invention and the merits thereof and also to acquire a knowledge of the details of construction of the means for effecting the result,reference is to be had to the following description and accompanying drawings, in which:

Figure 1 is a perspective view showing the operation of the device; Fig. 2 is a detail perspective view of the device when detached; and, Fig. 3 is a transverse sectional view showing a modification in which the free end of the spring member fits loosely within a slot in a guideway secured to the pitman.

Corresponding and like parts are referred to in the following description and indicated in all the views of the drawings by the same reference characters.

Referring to the drawings, the numeral 1 designates a wheel or rotary member, and 2 a reciprocating member or treadle which is connected to the member 1 by means of a pitman 3 of any conventional construction. A spring member 4 extends longitudinally along the pitman 3 and has its upper end loosely connected thereto while its lowerend is rigidly connected to the treadle so as to form a fixed angle therewith. In the preferred construction the foot plate 2 is provided at one corner with an outwardly extending pin 5 upon which the pitman 3 is pivotally mounted. The lower end of the spring member 4 is provided with a casting 6 having a transverse groove 7 therein which is preferably located on one side of the casting and which is adapted to receive the stem 5. In order to form a rigid connection between these members, a set screw 8 is employed which passes through the casting 6 and enters the groove 7 so as to engage with the stem 5. The upper end of the spring 4 is provided with an elongated eye 9 which forms a guideway for the pin 10 projecting from the pitman 3. In the preferred construction, the eye 9 is formed by bending the end of the spring 4 as shown in Fig. 2.

A modification is shown in Fig. 3 in which the guideway is formed as a separate member and is secured directly to the pitman. This guideway 11 is formed with a slot 12 within which the upper end of the spring 4 loosely fits and is adjustably secured to the pitman by means of a rearwardly extending arm 13 and set screw 14. In order to adjust the length of the slot 12 blocks 15 are slidably mounted therein and are adapted to be held in any position by means of pins 16.

In the operation of the device, it will be apparent that while the angle which the pitman forms with the treadle 2 is constantly changing, the angle of the spring member 4 is fixed and that therefore the upper endof the spring member will be bent so as to exert a transverse pressure upon the pitman when the pin 10 reaches the limit of its sliding movement and engages with an end of the slot 9. Owing to the fact that the pitman will form an acute angle with the treadle when it has reached its lowermost position and an obtuse angle when at its uppermost position, it will be apparent that the transverse pressure of the spring member 4 will be exerted in opposite directions at these times and since this pressure is at approximately right angles to the force exerted by the pitman, a constant motion will be produced and all dead centers overcome.

The essential feature of the invention resides in the fact that the spring member 4 is so mounted as to exert a lateral pressure which has a tendency to swing the pitman about its connection with the treadle and turn the wheel 1 when a dead center would otherwise be produced, but except at such times does not influence the motion of the wheel, since it has a sliding engagement with the pitman.

It will 'be observed that the part 9 shown in Figs. 1 and 2, and the part 11 shown in Fig. 3, constitute members or heads embodying elongated openings establishing connection between the pitman and the upper end of the spring 4. These members, as they inclose the stud 10 and the spring 4, respectively, in the constructions above mentioned, form positive means for establishing the desired connection and there is little or no likelihood of-disengagement of the means connecting the pitman and spring for this reason.

Attention is directed to the fact the invention virtually comprises an attachment which may be applied to the given forms of sewing machines at present in use, by reason of the special construction of the device as hereunto set forth. The spring member 4 is virtually provided with a transverse clamp at its lower end, consisting of the parts 6, 7, and 8, said clamp being engageable with the pin 5 projecting laterally from the treadle 2. The form of the clamp member and the arrangement thereof is such that the same does not interfere with the feet when the latter are on the treadle in any way. The head at the upper portion of the spring member 4 and which has a horizontal elongated opening or eye therein is in line with the clamp 6.

Having thus described the invention, what is claimed as new is:

The combination of a rotary member, a reciprocating member, a pitman connecting the two and having a stud projecting laterally therefrom, and a spring member extending along the pitman and provided at one end with an enlarged portion having a slot formed therein, whereby it is detachably connected to the reciprocating member and held in a fixed position with relation thereto, while the opposite end of the spring is provided with a laterally elongated slot which fits loosely over the before mentioned stud projecting from the pitman, the sliding movement of the stud within the slot enabling the rotary member, pitman and reci rocating member to operate freely without being influenced by the action of the spring member except when the stud has reached the limit of its sliding movement within the slGt and the members are in the proper position for producing a dead center.

In testimony whereof we afiix our signatures in presence of two witnesses.

FREDRIOK W. DILL. JOHN R. HILL. [L. s.] Witnesses:

H. W. RAHMEIER, E. A. MOFARLAND. 

